In Jewish culture the repeated use of something makes it mundane. Holy things are to be handled differently, otherwise they are just as mundane as any other object.
Unlike the JWs who came to the wacky conclusion that the only name for G-d is the Tetragrammaton, we Jews have many names for the Creator. One of them is "God." But to use it often makes the name mundane. Pagans use the names of their gods over and over again, but not Jews. Jews do the opposite. We rarely utter our G-d's name.
When writing it we leave out a letter or the vowels or something like that so that it can differentiate it from frequent use. It also helps in case the material upon which the name gets written is destroyed, so the chance of deliberately putting the name at risk of being handled like refuse is limited. It's just culture.
The literal existence of G-d isn't necessary in Judaism as it is in Christianity. What is necessary is the goodness of G-d, and that can be brought about in the world by anyone, an atheist, an agnostic, a Gentile, and even a Jew. Another lesson for Jews from Job is to live life in the world as if G-d isn't going to help you and isn't there to help others. We might believe that G-d is, but that does no good if we aren't changing the world for the better. What good is belief and condemning others for disbelief when time can be better spent loving others for who they are instead of changing them and helping one another when there's need?